ALBERT

Description: The global navigation satellite system (GNSS)-interferometric reflectometry technique has been applied to retrieve snow depth, which has a high potential for application. The GNSS reflectometry classical algorithm retrieves the snow depth by extracting the frequency of the multipath signal and substituting it into an empirical formula. However, the retrieval errors of high and low snow depths are large due to the influence of factors such as surface vegetation and terrain environment. In this paper, we propose a snow depth retrieval algorithm based on a particle swarm optimized long short-term memory (PSO-LSTM) neural network. The algorithm extracted three characteristic parameters (frequency, amplitude, and phase) from the signal-to-noise ratio (SNR) data as inputs, and optimized the LSTM hyperparameters by the PSO algorithm to improve the retrieval accuracy for low snow depths and snow depths close to the antenna. The snow depth retrieval results of global positioning system L1 band SNR data collected from the P351 station in 2022 and AB33 station in 2017 were evaluated in this paper. The snow depth retrieval results of the PSO-LSTM algorithm for P351 station were in high agreement with the snow depth data provided by the snowpack telemetry network; the coefficient of determination () reached 0.986, and the root mean square error (RMSE) and mean absolute error (MAE) were 7.30 cm and 4.94 cm, respectively. Compared with the classical algorithm, the PSO-LSTM algorithm decreased the RMSE and MAE by 53.0% and 30.4% for the retrieval results of snow depths below 15 cm at the P351 station, and by 76.8% and 84.4% for the retrieval results of snow depths above 117 cm from the 1st day to the 137th day, respectively. Similarly, the RMSE, MAE, and for the 2017 retrieval results at AB33 station were 5.90 cm, 4.25 cm, and 0.965, respectively. Compared with the classical algorithm, the PSO-LSTM algorithm decreased the RMSE and MAE by 47.9% and 33.0% for the retrieval results of snow depths below 15 cm at the AB33 station, and by 75.4% and 82.3% for the retrieval results of snow depths above 56 cm from the day 46 to day 120. In addition, the snow depth retrieval algorithm was proposed in this paper does not require antenna height and empirical formulas to realize snow depth retrieval, and at the same time, the algorithm effectively improved the retrieval accuracy for both high and low snow depths with strong robustness.

Description: The Gram-positive, rod-shaped endophytic bacterium Cellulomonas sp. strain ATA003 was isolated from the endemic cactus Maihueniopsis domeykoensis seeds collected in the Coastal Atacama Desert, Chile. Here, we present a circular genome with a size of 4,084,881 bp and a GC content of 73.8% obtained by Nanopore sequencing.

Description: Geomechanics play an important role in any underground activity, such as carbon dioxide (CO2) and hydrogen (H2) geo-storage, owing to the considerable hazards linked to the injection and withdrawal of fluids into and from the subsurface. In order to quantify these risks, knowledge of full stress tensor is required. Yet, most of our stress information in the Australian target basins for geo-storage is limited to the stress orientations, while stress magnitude data is sparse. 3D geomechanical modelling has proved to be an invaluable tool for prediction of full stress tensor. Nevertheless, a model requires some stress magnitude data in order to tune the model to be representative of real stress state. In situations where stress magnitude data is lacking, this means that the model is susceptible to significant uncertainties. Herein, we present a novel strategy for stress modelling, which involves the utilisation of indirect data such as borehole breakouts, drilling-induced fractures, seismic activity records, and formation integrity tests to calibrate a 3D geomechanical model. We employ the northern Bowen Basin, an onshore basin in Queensland, Australia, as a case study for a comprehensive 3D geomechanical modelling approach. We assess all the indirect information in the model’s volume to narrow down the model predictions and find the most reliable stress state. This innovative approach is an important step forward in stress modelling of Australian basins, where lack of stress magnitudes is a great challenge for geomechanical assessment of geo-storage.

Description: Chromium (Cr) leached from iron (Fe) (oxyhydr)oxide-rich tropical laterites can substantially impact downstream groundwater, ecosystems, and human health. However, its partitioning into mineral hosts, its binding, oxidation state, and potential release are poorly defined. This is in part due to the current lack of well-designed and validated Cr-specific sequential extraction procedures (SEPs) for laterites. To fill this gap, we have (i) first optimized a Cr SEP for Fe (oxyhydr)oxide-rich laterites using synthetic and natural Cr-bearing minerals and laterite references, (ii) used a complementary suite of techniques and critically evaluated existing non-laterite and non-Cr-optimized SEPs, compared to our optimized SEP, and (iii) confirmed the efficiency of our new SEP through analyses of laterites from the Philippines. Our results show that other SEPs inadequately leach Cr host phases and underestimate the Cr fractions. Our SEP recovered up to seven times higher Cr contents because it (a) more efficiently dissolves metal-substituted Fe phases, (b) quantitatively extracts adsorbed Cr, and (c) prevents overestimation of organic Cr in laterites. With this new SEP, we can estimate the mineral-specific Cr fractionation in Fe-rich tropical soils more quantitatively and thus improve our knowledge of the potential environmental impacts of Cr from lateritic areas.

Description: A large dataset of detrital zircon U–Pb ages (N = 5940) of Aptian-Albian strata of the Colombian-Ecuadorian retroarc region suggests that these rocks were sourced from Proterozoic cratonic and Permian–Triassic to Cretaceous rocks of the Andean proto-Cordilleras. The nonconformity between Aptian-Albian strata and Proterozoic rocks of the Garzón Massif indicates the existence of positive relief in this region. Topographic highs could have caused local basin compartmentalization and the prevalence of a localized provenance of coeval strata. Areas of positive relief were seemingly exposed to intense chemical weathering as suggested by the high Chemical Index of Alteration values, and low Rb/Sr and SiO2/Al2O3 ratios of analysed strata. Our results highlight the value of provenance analysis to study the ancient topography of retroarc systems and open the avenue for further research on the role of extensional tectonics in the topographic and basin evolution in the Andes.

Description: Using the electron density (Ne) observations from the Defense Meteorological Satellite Program, and Constellation Observing Systems for Meteorology, Ionosphere, and Climate mission and simulations from the Thermosphere Ionosphere Electrodynamic General Circulation Model. we investigate the dynamic evolution of the polar tongue of ionization (TOI) from double to single structures at different altitudes during a geomagnetic storm. The modeled Ne depicted that double and single TOIs occurred at altitudes above 300 km, respectively. During the northward turning of interplanetary magnetic field (IMF) Bz, the afternoon TOI disappeared and the morning TOI was reduced. The plasma transport due to neutral winds and ambipolar diffusion facilitated (prevented) the depletion of plasma density of the morning TOI at 300 (500) km, with a relative contribution of 42.8% and 28.6% (−15.4% and −76.9%), respectively. Downward E × B drifts led to an enhancement/reduction of plasma density in the storm enhanced density region in the lower/upper ionosphere. During the duskward turning of IMF By, the morning TOI could be mostly attributed to the anti-sunward plasma drifts (75.8% at 300 km, 100% at 500 km), with a relatively stronger role of the zonal component than that of meridional E × B drifts. The upward E × B drifts were important/ignorable in the upper/lower ionosphere. Both the neutral winds and ambipolar diffusion resulted in an accumulation of plasma density of the morning TOI at 300 km indirectly (24.2%), however, their roles were minor at 500 km

Description: Natural alteration of zircon takes place in melts or fluids either via dissolution coupled with overgrowth or via a coupled dissolution-reprecipitation process. The latter results in the zircon being partially or totally replaced by new, compositionally re-equilibrated zircon or a new mineral phase or both. In this study, fragments (50–300 μm) from a large, inclusion-free, clear, 520–530 Ma euhedral zircon with light radiation damage from a nepheline syenite pegmatite, Seiland Igneous Province, northern Norway, were experimentally reacted in 20 mg batches with 5 mg of ThO2 + ThSiO2 + SiO2 and a series of alkali-bearing fluids in sealed Pt capsules at 900 °C and 1000 MPa for 6–11 days in the piston cylinder press using a CaF2 setup with a cylindrical graphite oven. ThO2 + ThSiO2 + SiO2 was present at the end of the experiment. In experiments involving H2O, H2O + NaCl, H2O + KCl, and 2 N KOH, no reaction textures formed other than a slight dissolution of the zircon grain fragments. Experiments involving 2 N NaOH, Na2Si2O5 + H2O, and NaF + H2O resulted in zircon reaction textures with varying degrees of intensity, which took the form of partial replacement by compositionally modified zircon via a coupled dissolution-reprecipitation process. In the NaF + H2O experiment some overgrowth also occurred. Altered zircon is separated by sharp compositional boundaries from unaltered zircon. Secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis indicates that, relative to the unaltered zircon, the altered zircon is strongly enriched in Th, and heavily to moderately depleted in U and (Y + REE). In all the experiments, 206Pb (3–5 ppm in unaltered zircon) is depleted in the altered zircon to below the SIMS detection limit and to at or below the LA-ICP-MS detection limit. Hafnium and Ti concentrations in the altered zircon retained the same approximate value (within error) as the original zircon. The results from these experiments demonstrate that zircon can be compositionally modified by alkali-bearing and alkali-F-bearing fluids via a coupled dissolution-reprecipitation process. Near to total loss of radiogenic Pb via such processes under high-grade conditions resets the internal zircon geochronometer. Although the end result is the same as with zircon overgrowth, i.e. the production of new generation zircon at the time of a metamorphic/metasomatic event, such replacement processes can explain incomplete isotopic ‘resetting’; inclusion production through unmixing of solid solutions in metastable zircon compositions; and ‘ghost’ textures that preserve initial growth features but with isotopic disturbance. Diagnostic replacement features produced in experiments, such as interface geometries between altered and unaltered zircon, provide markers of the mechanism and aid in zircon interpretation. A major implication from this study is that if zircon with low radiation damage can be metasomatically altered under high-grade conditions, this would have important consequences with respect to zircons presumed role as an impregnable container for mineral inclusions. Namely the mineral inclusions contained within zircon could also be altered, reset as a geochronometer, or even replaced by another mineral.

Description: To investigate the long-term stability of deep rocks, a three-dimensional (3D) time-dependent model that accounts for excavation-induced damage and complex stress state is developed. This model com- prises three main components: a 3D viscoplastic isotropic constitutive relation that considers excavation damage and complex stress state, a quantitative relationship between critical irreversible deformation and complex stress state, and evolution characteristics of strength parameters. The proposed model is implemented in a self-developed numerical code, i.e. CASRock. The reliability of the model is validated through experiments. It is indicated that the time-dependent fracturing potential index (xTFPI) at a given time during the attenuation creep stage shows a negative correlation with the extent of excavation- induced damage. The time-dependent fracturing process of rock demonstrates a distinct interval effect of the intermediate principal stress, thereby highlighting the 3D stress-dependent characteristic of the model. Finally, the influence of excavation-induced damage and intermediate principal stress on the time-dependent fracturing characteristics of the surrounding rocks around the tunnel is discussed. Ó 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Description: The Lindero deposit is located in the Puna plateau, northwest Argentina, at the southern end of the Central Volcanic Zone of the Central Andes. The high-K calc-alkaline dioritic composition of the subvolcanic intrusions, the shallow emplacement depth (〈 1.5 km), and the gold-rich and copper-depleted mineralization style suggest that the Lindero deposit is a porphyry gold deposit. Porphyry gold deposits are scarce worldwide and the factors controlling their formation are still poorly known. Here we present a detailed study of fluid inclusions in order to characterize the mineralizing fluids that precipitated the Au mineralization at Lindero. Different types of fluid inclusions in quartz veins (A-type and banded quartz), which are associated with the K-silicate alteration, were analyzed using Raman spectroscopy, microthermometry, and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry). Four inclusion types can be recognized in quartz veins: (i) Salt melt inclusions, which are characterized by a dense packing of daughter minerals (mainly Fe-chloride, sylvite, halite, anhydrite, and hematite), by a distorted vapor bubble, and by the lack of liquid phase; (ii) Halite-bearing inclusions which contain liquid, vapor, and halite; (iii) Two-phase aqueous inclusions that contain liquid and vapor; (iv) Vapor-rich inclusions containing only vapor. The inclusion types are related to different stages of hydrothermal evolution. Stage 1 is the main mineralization stage, characterized by vapor-rich inclusions coexisting with salt melt inclusions. Salt melt inclusions commonly show total homogenization temperature (ThL) 〉 1000 °C. This Na-K-Fe-Cl-rich highly saline brine (~ 90 wt% NaCl eq.) was of magmatic origin and responsible for the Au mineralization. Two later stages involving cooler fluids (ThL 〈 300 °C) and gradually lower salinities (from 36.1 to 0.2 wt% NaCl eq.) trapped by halite-bearing and two-phase aqueous inclusions during stages 2 and 3, respectively, correspond to a late magmatic-hydrothermal system, that is probably related to a deep supercritical fluid exsolution. Salt melt inclusions represent the most likely parental fluid of K-silicate alteration and associated Au mineralization at Lindero. This uncommon type of fluid must have played an important role in Au transport and precipitation in shallow porphyry gold deposits.

Description: Osmium isotope and highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundance data are reported for picrites and basalts from the ∼132 Ma Etendeka large igneous province (LIP) and the ∼60 Ma North Atlantic Igneous Province (NAIP). Picrite dykes of the Etendeka LIP have HSE abundances and 187Os/188Os (0.1276 to 0.1323; γOsi = -0.5 to +3.1) consistent with derivation from high-degree partial melting (〉20 %) of a peridotite source with chondritic to modestly supra-chondritic long-term Re/Os. High-3He/4He NAIP picrites from West Greenland represent large-degree partial melts with similarly elevated HSE abundances and 187Os/188Os (0.1273 to 0.1332; γOsi = -0.2 to +3.9). Broadly chondritic Os isotope ratios have also been reported for the ∼132 Ma Paraná LIP and the ∼201 Ma Central Atlantic Magmatic Province (CAMP). Consequently, LIP associated with Atlantic Ocean opening derive, at least in part, from partial melting of peridotite mantle distinct from the depleted mantle associated with mid-ocean ridge basalt volcanism. Modern locations with high-3He/4He (〉25RA) include ocean island basalts (OIB) from Ofu (Samoa), Loihi (Hawaii) and Fernandina (Galapagos) in the Pacific Ocean, and from Iceland, which is considered the modern manifestation of NAIP magmatism. Unlike Etendeka and NAIP picrites, these modern OIB have Sr-Nd-Pb-Os isotopes consistent with contributions of recycled oceanic or continental crust. The lower degree of partial melting responsible for modern high-3He/4He OIB gives higher proportions of fusible recycled crustal components to the magmas, with radiogenic 187Os/188Os and low-3He/4He. The high-3He/4He, incompatible trace element-depleted mantle component in both LIP and OIB therefore also has long-term chondritic Re/Os, which is consistent with an early-formed reservoir that experienced late accretion. Atlantic LIP (CAMP; Paraná-Etendeka; NAIP) provide geochemical evidence for a prominent role for mantle plume contributions during continental break-up and formation of the Atlantic Ocean, a feature hitherto unrecognized in other ocean basin-forming events.